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134 Cards in this Set

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Where is the most resistance in the airways?
Medium sized bronchi. Smallest bronchi are not the most resistance because of their parallel orientation
What is the function of surfactant? How does it work?
Reduces surface tension by disrupting intermolecular forces between liquid molecules.

Increases compliance of the alveolus.
What is the main component of surfactant?
phospholipids (80%) - main one is DPCC
What is neonatal respiratory distress syndrome?
Lack of surfactant in premature infants causes atelectasis, difficulty reinflating lungs (decreased compliance), hypoxemia because of decreased V/Q
What is the equation that relates pressure, airflow, resistance?

Units of resistance?
Q = delta P/R

R = cmH20/L/min
Which volumes cannot be measured by spirometry?
Anything that involves residual volume: Residual volume, functional residual capacity, total lung capacity
Equation to calculate physiologic dead space
Vd = Vt x (PACO2 - PECO2)/PACO2

A = alveolar gas
Vt = tidal volume
What is inspiratory capacity the sum of?
Tidal volume + inspiratory reserve volume
What makes up FRC?
Functional residual capacity = RV + Expiratory reserve volume
What makes up vital capacity
Sum of ERV + TV + IRV
What is normal FEV1/FVC
80%
Asthma - obstructive or restrictive? what happens?
Asthma is obstructive lung disease. Reduced FEV1, reduced FVC, low FEV1/FVC ratio
Fibrosis - obstructive or restrictive? What happens?
Restrictive. Reduced compliance. Everything reduced almost same, so FEV1/FVC ratio stays normal or increased.
Muscles of inspiration
diaphragm (pushes everything down), external intercostals (elevate)
Muscles of expiration
Expiration is normally passive. Active respiration is abdominal muscles and internal intercostal muscles.
Transpulmonary pressure = ?
Alveolar pressure - intrapleural pressure
What is hysteresis?
Inflation follows a different curve than deflation of the lung
What happens to compliance in emphysema
Lung compliance increased (tendency of lungs to collapse decreased); new, higher FRC comes and chest becomes barrel shaped
Fibrosis and compliance?
Compliance is decreased, tendency to collapse is increased, so there is a lower FRC
At rest, what are the pressures of interpleural cavity and alveoli relative to atm pressure?
Alveolar pressure = atm pressure; intrapleural pressure is negative because the lungs want to collapse and the chest wall wants to expand
When you are inspiring, what happens to the pressures as the thoracic space increases?
lung volume expands, so the pressure in the lungs becomes less than atm pressure, and the pressure gradient allows air to flow into lungs
During expiration, what happens to the alveolar and intrapleural pressures?
alveolar pressure becomes greater than atm pressure and air flows out of the lungs
COPD - obstructive or restrictive? what happens to compliance? FEV1/FVC ratio?
obstructive; compliance increases --> barrel chest; FEV1/FVC ratio down
What is the P02 in the air? in the alveoli air? in the arterial blood? in the venous blood?
Air = 150 mmHg; alveoli = 100mmHg; blood = 100; venous = 40
What is the PCO2 in air? in alveoli? in arteries? in veins?
Air = 0; alveoli = 40; arteries = 40; veins = 46
What is methemoglobin?
Fe2+ is normal state of iron in heme moiety of hemoglobin; methemoglobin is iron in Fe3+ state
What limits the amount of O2 that can be carried in the blood?
O2 saturation of hemoglobin
What is the Carboxyhemoglobin?

What is carbaminoHb?
carboxy = CO + Hb

carbamino = CO2 + Hb
What is the major form in which CO2 is transported to the lungs?
HCO3-

H20 + CO2 --> H2CO3 --> HCO3- + H+ (happens in venous blood)
What buffers the H+ produced when CO2 breaks down to bicarbonate and H+?
deoxyhemoglobin
Zone 1 pressures
P alveolar > Parterial > P venous
Zone 2 pressures
P arterial > P alveolar > P venous
Zone 3 pressures
P arterial > P venous > P alveolar
Do lungs vasoconstrict or vasodilate in response to hypoxia?
Vasoconstrict; this way poorly ventilated regions will not have too much perfusion either; this happens when PO2 falls to low levels, esp when pH is more acidic (less than 7.4) as happens when pCO2 levels are high.
How does V/Q ratio change from apex to base of lung?
Apex: High ventilation, low perfusion = high V/Q ratio

Base: Low ventilation, high perfusion = Low V/Q ratio
Which part of the brain controls breathing?
brain stem
Where are central chemoreceptors? What stimuli cause them to increase breathing?
Medulla; hyperventilation caused by decreased pH, increased pC02
Where are peripheral chemoreceptors? What stimuli cause them to increase breathing?
carotid and aortic bodies; decreased p02, increased CO2, decreased pH
What is the Hering Breuer reflex?
Lung stretch receptors are stimulated by distention of lungs and produce a reflex decrease in breathing frequency
Where are irritant receptors located? What stimulates them?
Located between airway epithelial cells; stimulated by noxious substances (dust, pollen)
Which receptors are activated to stimulate breathing during exercise?
joint/muscle receptors activated at beginning of exercise
What kind of drug will counter the effects of asthma (bronchoconstriction)?
B2 adrenergic agonist - produces relaxation of the bronchioles
If there is an embolism that blocks blood flow to the left lung, what is the pO2 going to be of the alveoli?
Left lung PAO2 will be the same as the inspired air because there is not going to be any gas exchange between the alveoli and the pulmonary capillary blood if there is no perfusion.
Why do pulmonary vascular resistance and blood flow vary along the vertical length of the lung?
gravitational effects
barrett
How is pulmonary vascular resistance affected by changes in pulmonary intravascular pressure (exercise?)
goes down
barrett
How is PVR affected by positive pressure ventilation?
goes up
barrett
How is PVR affected by Nitric Oxide?
goes down
barrett
Does hypoxia increase or decrease PVR? When is this beneficial? When is this detrimental?
Hypoxia increases PVR. Good for fetal circulation; bad for high altitude
barrett
What's the mean pulmonary arterial pressure?

Mean Left Atrial Pressure?
PA - 15mmHg
LA - 5 mmHg
Barrett
From the apex to the base of the lung, which of the pressures remains unchanging: P arterial, alveolar, or venous?
alveolar
Barrett
At what volume is resistance to pulmonary blood flow the least?
Functional residual capacity. It increases as the lung is inflated or deflated.
Barrett
When the lung is inflated from FRC, what is the reason for the increase in PVR?
Alveolar capillaries are getting compressed (they are embedded in the expanding alveolar walls)
Barrett
When the lung is deflated from FRC, what is the reason for the increase in PVR?
The extra-alveolar capillaries (veins and arteries) are becoming compressed because the intrapleural pressure becomes positive with forced expiration; also radial traction forces become smaller which mean the vessels aren't held open as well.
Barrett
Why do pulmonary vascular resistance and blood flow vary along the vertical length of the lung?
gravitational effects
barrett
How is pulmonary vascular resistance affected by changes in pulmonary intravascular pressure (exercise?)
goes down
barrett
How is PVR affected by positive pressure ventilation?
goes up
barrett
How is PVR affected by Nitric Oxide?
goes down
barrett
Does hypoxia increase or decrease PVR? When is this beneficial? When is this detrimental?
Hypoxia increases PVR. Good for fetal circulation; bad for high altitude
barrett
Does extra-alveolar PVR go up when lungs go toward TLC or toward RV?
RV - Extra-alveolar PVR goes up when the lungs are deflated from FRC.
Barrett
Does alveolar PVR go up when lungs go toward TLC or toward RV?
TLC - alveolar PVR goes up when the lungs are inflated from FRC
Barrett
When is vasoconstriction of lungs in response to hypoxia good? When is it bad?
Good in fetal circulation, when blood needs to be shunted away from the lungs. Bad in high altitude, when even well ventilated regions of the lung are hypoxic
barrett
In hypoxia, which side of the heart has increased work when PVR increases?
Right heart (Right heart pumps blood into pulmonary system, and it's working against a higher resistance to get the blood out)
Barrett
What is the difference between interstitial and alveolar edema?
Interstitial = thickening of wall parenchyma

Alveolar = fluid accumulation in alveoli

Result of any pulmonary edema = impaired gas transfer
Barrett
Factors that lead to pulmonary edema (5)
1. Permeability - infections, toxins that destroy the integrity of the capillary endothelium
2. Capillary hydrostatic pressure increases --> fluid goes out of capillary
3. Interstitial hydrostatic pressure decrease --> fluid goes out of capillary
4. Plasma osmotic pressure decrease --> fluid goes out with it
5. Interstitial oncotic pressure increase --> fluid goes out to balance it
6. lymphatic insufficiency
barrett
What circulation is sensitive to acetylcholine and tachykinins?
tracheobronchial circulation - this is the reason that there is increased permeability of the tracheobronchial blood flow during asthma
barrett
What is the functional importance of pulmonary arteries and pulmonary veins running separately?
prevents gas exchange/diffusion between arteries and veins; arteries run next to airways and veins run seperate
Causes of pulmonary edema (from lecture notes)
1. elevated intravascular pressure (ex. left heart failure)
2. Blocked lymphatic drainage
3. Absence of surfactant (only in pulm. circulation)
4. Increased capillary permeability (ex. infection)
5. Loss of plasma proteins
What is Fick's Law
Vgas = (A/T)D(pA - pB)

V = net rate of gas movement
What is the partial pressure of O2 and CO2 in mixed venous blood?
O2 = 40
CO2 = 46
What is the partial pressure of O2 and CO2 in mixed alveolar air?
O2 = 100
CO2 = 40
Why does CO2 diffuse at the same rate as O2, even though the pressure gradient is small? (CO2 =6 blood to air and O2=60 air to blood)
CO2 is about 20 times more soluble in blood than O2, and thus has a larger diffusion coefficient than O2.
What is diffusion equilibrium?
pA = pB
Why doesn't diffusion normally limit the rates of O2 uptake and CO2 elimination in the lungs?
It takes about 1/4 second to reach diffusion equilibrium between the alveoli and the blood, and the exposure in each cardiac cycle is 3/4 seconds.
During exercise, is the rate of O2 uptake or CO2 elimination diffusion limited?
Neither is diffusion limited for a normal person because even though cardiac output can increase and shorten the time each RBC is exposed to alveolar air, it is still 1/4 second. In trained athletes, it is possible to get diffusion limitation/hypoxia.
What are three circumstances in which gas exchange can become diffusion limited?
1. trained athlete doing heavy exercise (CO becomes too high and RBCs don't get enough exposure to alveolar air because they are moving so fast.
2. diffusion barrier becomes thicker (pulmonary edema). O2 affected more than CO2.
3. High altitude - smaller O2 gradient driving transfer from alveoli to blood.
Is O2 uptake perfusion limited or ventilation limited?
Perfusion. O2 uptake can be increased more by increasing rate of pulm. perfusion than by increasing rate of ventilation.
Which term in Fick's Law can you use CO to measure?
A/T (diffusing capacity of alveolar surface)

pCO in blood is very low so it's transfer is diffusion limited
What does it mean when the O2 binding curve of Hb is shifted to the right? What factors can cause this to happen?
decreased O2 affinity, increased P50 (pO2 at which 50% Hb saturation). Caused by increased CO2, decrease pH, DPG, elevated temp
Equation for O2 capacity
1.34 mlO2/gm Hb x Hb concentration = 20.1 mlO2/100gm blood

Normal Hb saturation is 15gm/100ml blood
Equation for O2 content
O2 capacity (1.34 x Hb conc) + dissolved O2 (O.003 x pO2)
3 forms of CO2 carried in blood?
dissolved CO2, carbaminoHb, HCO3-

HCO3- is predominant form in arterial and venous blood
Which acids are secreted by lungs and kidney (fixed or volatile)
Kidney - fixed
Lungs - volatile (ex. H2CO3)
What are the roles of the lungs and kidneys in maintaining the plasma pH at 7.4?
lungs maintain pCO2 by adjusting rate of alveolar ventilation; kidneys maintain HCO3-
What happens in respiratory acidosis?
Rise in pCO2 of plasma, usually resulting from impaired gas exchange in lungs (asthma, pneumonia, emphysema, hypoventilation)
What happens in respiratory alkalosis?
Lowering of pCO2 from an increase in alveolar ventilation not matched by a proportionate increase in CO2 production (from hyperventilation in high altitude, childbirth, etc)
In chronic acid-base disturbances (respiratory acidosis or respiratory alkalosis) how does HH equation adjust to compensate?
The kidney either lowers plasma HCO3- (alkalosis) or elevates plasma HCO3 (acidosis) to compensate
In a respiratory acidosis with elevated pCO2 and HCO3-, which is the primary problem?
elevated pCO2. elevated HCO3- is the compensation by the kidney to keep the pH as close to 7.4 as possible.
How does the diffusion rate of CO2 affect the diffusion rate of O2?
It doesn't; each gas diffuses independently of other gasses.
If VCO2 (rate of CO2 production) remains constant, what relationship remains reciprocal (use alveolar ventilation equation)
Alveolar ventilation and arterial/alveolar pCO2 will be inversely proportional
Why do we use Carbon Monoxide to measure A/T in Fick's Law and not pO2 or pCO2?
pO2 and pCO2 change along the length of the alveolar capillary; CO partial pressure changes very little along the length of the alveolar capillary
Is the relationship between pO2 and O2 saturation of Hb linear or nonlinear?
nonlinear
What is the Bohr effect?
Acid pH reduces O2 binding to Hb more in the tissues than in the lungs
What is the difference between acute and chronic respiratory acidosis?
acute = no renal compensation
chronic = renal compensation complete (takes about a week)

Respiratory alkalosis is compensated by renal reduction of HCO3 within 2 days
What is the relationship between V/Q and pO2 and V/Q and pCO2?
As V/Q decreases, alveolar pO2 goes down and pCO2 goes up.

The ventilation-perfusion ratio decreases down the lung.
Does high V/Q ratio affect O2 or CO2 transfer more? What about shunts?
High V/Q affects CO2 transfer more because alveoli can't help remove CO2 from blood if they are not being perfused. Shunts affect O2 transfer more.
Five causes of hypoxemia (low O2 in blood)
1. Inadequate pO2 in inspired air (high altitude)
2. hypoventilation
3. diffusion abnormalities (pulmonary edema)
4. V/Q nonuniformity
5. shunt
What is the conducting portion of the respiratory system?
nasal cavities, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles

warm, humidify air
What is the respiratory portion of the respiratory system?
respiratory bronchioles, alveoli ducts, alveolar sacs, alveoli

exchange gas
which cartilage is most important in the larynx (open and close glottis)
arytenoids
What is the only muscle that opens the vocal cords (sole abductor)
posterior cricoarytenoid
Principle adductor of vocal cords
lateral cricoarytenoid
what is the main innervation of the larynx? Which side has the nerve deep in the chest?
recurrent laryngeal nerves - left goes around aorta deep in chest (injury in chest can cause vocal cord paralysis)

Exception: cricothyroid innervated by superior laryngeal nerve
what is the only cartilage that goes all the way around the larynx?
cricoid cartilage
what is the histology of the epiglottis?
first 2/3 - non keratinized stratified squamous

last 1/3 - pseudostratified columnar ciliated
true vocal cords epithelium?

false vocal cord epithelium?
true: nonkeratinized stratified squamous

false: PSCC (also has glands so some mucus produced here during cold)
Which bronchus is more steep?
Left - distance greater than right before branching into segmental bronchi
What is the angle of Lewk?
carina splits here
which vessels have same diameter as bronchi?
pulmonary arteries
What is the relation of the right/left pulmonary arteries and the bronchi?
Right PA goes OVER bronchus; left goes under

pulmonary veins run in between segments of the lung
Segments of R and L lobe
R = 3,2,5
L = 4 (2 of lingula),4
Bronchus vs trachea
bronchus: irregular lumen, alveoli surrounding airway, cartilage plates

trachea: smooth lumen, muscle all the way around, Goblet cells, C shaped rings of cartilage

bronchioles - irregular lumen, but NO cartilage plates, CLara cells
Histology of terminal bronchiole
simple cuboidal cilliated, clara cells, macrophages, no cartilage
Type I vs Type II alveolar cells
Type I: epithelial cells that cover alveolus (Blood air barrier)

Type II: produce surfactant, help keep alveolus open
what allows for collateral ventilation in the lungs?
Pores of Kohn
does the alveoli have mucus producing cells?
no
Where do bigger particles generally deposit in the airway? What about smaller particles?
bigger particles (larger than 5 microns) in nasopharynx; smaller in bronchi, airways, alveoli
Function of periciliary layer
allows cilia to beat
What is 9+2 cilia?
9 outer doublets, one central pair of microtubules; each has dynein arms to help them move
What is 9+0 cilia?
no central pair of microtubules; can only sense or move in circles
What is the role of Ca and cAMP in cilia?
increase these two and you see increased ciliary beating
What are the three things in Primary ciliary dykinesia (formerly Karagener syndrome)
situs inversus, sinusitis, bronchiectasis (dilation)

all related to malfunction of cilia in development
What is the mutation in cystic fibrosis?
CFTR gene, problem with chloride channels so water cannot go out into periciliary layer
If you breath in dry, cold air, what happens to mucociliary clearance?
it stops - need ventilators with warm and humidified air
Treatment of mucociliary dysfunction?
B-agonists and methylxanthines, recombinant DNase, amiloride (increases intracellular Ca)
What's alveolar proteinosis?
Antibodies that are against GM-CSF, so alveolar macs can't clear alveolar space
Silicosis
eggshell calcification on hilum, dust, occupational problems
Which lymph nodes are located at the carina?
tracheobronchial lymph nodes
What is a lobule supplied by?
bronchiole
Which muscle is not innervated by right recurrent laryngeal nerve?
cricothyroid
The inferior border of a lung projects into the ______ pleural recess.
Costodiaphragmatic
the only muscle that abducts the vocal ligament is
posterior cricoarytenoid
What are the components of the blood air barrier?
fused basal lamina, type 1 alveolar cell
Which volumes are increased in obstructive lung disease?
RV, FRC, TLC
total compliance =
air-alveolar